Precision grinding machine



Oct. 24, 1950 G. ASBRIDGE PRECISION GRINDING MACHINE Filed May 5, 1948Wm M.

Patented Oct. 24, 1950 PRECISION GRINDING .MACHINE George HerbertAsbridge, Altrincham, England,

assignor to The Churchill Machine Tool Company Limited, Altrincham,England, a British company ApplicationMay 5, 1948, Serial No. 25,198 InGreat Britain May 19, 1947 1 Claim.

This invention relates to precision grindin machines and has for itsobject to provide improved means for grinding workpieces to sizeautomatically in either internal or external grinding machines.

In accordance with my invention, the machine is provided with upper andlower tables, the upper one being hingedly or pivotally mounted upon thelower table and having thereon means for carrying the workpiece to beground, the lower table having mounted thereon a former upon which apart upon the upper table rests so that if the former is traversed ormoved so that the said part is moved from a low position on the formerto a high position, theupper table will be rocked about its pivots andthe workpiece thereon will be ground to size and each subsequent piecewill be ground to the same size for a similar movement or" the former.

The invention further comprises a combined electrical and hydrauliccontrol means for the machine which gives a fully automatic cycle to themachine.

Referring to the accompanying explanatory drawings Figure 1 is a generalview of a grinding machine with control means giving a fully automaticcycle of operations after the cycle has been commenced with a handcontrolled movement.

Figure 2 is an end view of the machine.

Figure 3 is an electrical diagram of the control connections,

The grinding machine comprises an upper table a carrying a headstock band tailstock c and supports d into which each workpiece e is placed sothat it can be engaged by the tailstock spindle or centre ,f andsupported between the headstock and tailstock centres clear of thesupports d.

The grinding wheel head g is carried rigidly on the part h. The grindingwheel is shown at z.

The table a is pivotally carried by the lower table 7' which can slidealong the machine bed in the usual manner to move the workpiece acrossthe grinding wheel 2'. If desired the pivotal connection between thetables a and 7' may be constituted by knife edges. Upon the lower table7' is longitudinally traversible a slide is having a former m mounted.thereon upon which rests a part n, known as a knudger, secured to theunderside of the upper table adjacent to the edge of the table oropposite to that at which the grinding wheel i is situated. The pivotalsupports of the upper table are at the side thereof at which thegrinding wheel is situated.

The slide k is coupled to a piston p in a double 2 acting hydrauliccylinder q. The fiow of hydraulic fluid to and its exhaustion from thecylinder (1 is by way of the pipes 'r., s leading to a cylinder tcontaining a valve u moved in one direction by a solenoid 22 and in theother direction by a spring in. Pressure fluid is supplied to thecylinder t by the pipe :0 fed by the gear type pump z are the exhaustpipes leading from the ends of the cylinder t.

The tailstock c has its centre moved in a, direction to engage theworkpiece by the spring 4 and in the other direction by a hydraulicpiston 5 in a cylinder 6 having a fluid connection I leading to a fluidcontrol valve 8 which is moved to the right in Figure 1 by the handlever 9 and to the left in such figure by the solenoid in acting throughthe hand lever. As shown, the valve 8 is in a position in which pressurefluid from the pump y is passing by way of the pipe H and the cylinder 2to the pipe I and so to the cylinder 6 in the tailstock, to hold thetailstock centre 1 in its inoperative withdrawn position. When the saidcentre 1 is in this position a contact plate 13 on the spindle of thepiston 5 is clear of the contacts l4 so that an electric circuit throughthe latter is broken.

A contact plate it upon the stem of the piston p is adapted in oneposition of the plunger to bridge the electric contacts it and in theother position of the piston to bridge the contacts H.

The stem of the piston p also carries a cam l8 which 'when the plungeris in its right hand position engages and operates a contact plate I9causing it to close contacts 25.

The operation of the machine is controlled as follows: When the handle 9is moved to the right in Figure 1, the pipe I is put in communicationwith the exhaust pipe 2! and so the cylinder 6 is exhausted, thusallowing the spring 4 to advance the tailstock centre f and engage theworkpiece carried on the supports d and carry it so that it is supportedbetween the head stock and tailstock centres. The contact plate G3 nowcloses the contacts i i which as shown in Figure 3 connects the solenoido between the mains 22, 23 so that it is energised. The feed valve 11.is moved against the spring to and causes pressure fluid to pass frompipe at to pipe 1' (s being exhausted). This results in the piston pbeing moved to the right and traversing the former m, up which the partit rides and tilts the table a. The workpiece e is therefore fed againstthe grinding wheel and ground to size. At the end of the stroke ofpiston p, contacts 29 are closed by the plate [9 operated by the cam l8.Contacts [6 have been opened and contacts I! closed. Closing of contactsI! energises the relay 24 which closes the normally open contacts 25 and26. 25 is in series with the solenoid l0 and 26 is connected across thecontacts ll. 21 is a dwell relay which is energised when the contacts 20are closed and after a predetermined interval of time opens the contacts28 and deenergises the solenoid u so that the feed valve u is reversedand the piston p returned to its initial position with the former mclear of the part 12. When this occurs the contacts I! are opened and [6closed. Relay 24 is maintained in circuit via contacts 26. When contactsiii are closed, the solenoid i0 is energised and pressure fluid passedvia the valve 8 to the tailstock cylinder 6 to cause the tailstockcentre to be withdrawn from the workpiece e which drops on to thesupports d. At the same time the contacts M are opened whichde-energises the entire electrical circuit. This is now in correctcondition to repeat the cycle after the handle 9 has been moved.

What I claim is:

A precision grinding machine comprising, in

combination, a grinding wheel, an upper table, a

tailstock and a headstock carried by said table, a lower table, apivotal connection between the upper and lower tables at the grindingwheel side of the tables, a former, a slide carrying said formertraversible longitudinally upon said lower table at the side of thelatter opposite to that at which the grinding wheel is situated, a partupon the underside of the upper table resting on said former so as totilt the upper table as the slide is traversed, a spring moving thetailstock centre to its operative position, a hydraulic plungerwithdrawing said centre from its operative position with means closingan electric circuit when the centre is in its service position, a valvecontrolling the hydraulic fluid operating said plunger, a hand lever formoving said valve in a direction to release pressure fluid from saidplunger, a solenoid to operate said valve to cause pressure fluid to beapplied to said plunger, a hydraulic plunger traversing theformer-carrying slide, closing two sets of contacts when the former istraversed to its position to give maximum tilt to the upper table andclosing one set of contacts when the former is in its out of serviceposition, a valve controlling the passage of hydraulic fluid to one orother side of said last mentioned plunger, such valve being moved by asolenoid against spring pressure, one of the two sets of contactscontrolled by the plunger of the slide carrying the former closing acircuit through a dwell relay controlling contacts in the circuit of thesolenoid operating the slide plunger, whilst the other of the two setsof contacts close a circuit through a relay which closes normally-opencontacts in the circuit of the solenoid operating the valve of thetailstock plunger and normally-open contacts between said other of thetwo sets of contacts, so that the slide plunger has its motion reversedafter the slide has moved the former to a maximum extent and finally thetailstock plunger control valve solenoid is energised, causing thetailstock centre to be withdrawn and the complete electrical circuitde-energised.

GEORGE HERBERT ASBRIDGE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,082,734 Grifling et a1 June 1,1937 2,178,848 Booth Nov. 7, 1939 2,185,490 Flygare Dec. 12, 19392,448,551 Schroeder Sept. '7 ,1943

